Virtually all patterns of distribution of left ventricular hypertrophy may represent expressions of genetically transmitted hypertrophic cardiomyopathy. Furthermore, the morphologic appearance of the left ventricle is particularly variable and markedly dissimilar in the large majority of closely related individuals with the genetically transmitted form of hypertrophic cardiomyopathy. This marked morphologic variability in closely related patients suggests that in screening families for hypertrophic cardiomyopathy both M-mode and two-dimensional echocardiography should be utilized.